New Insight into Aluminium Citrate/Polyacrylamide Gels for Fluid Control

Abstract

Abstract Aluminium citrate/polyacrylamide gels are found to be more sensitive and less robust than similar chromium systems. The main motivation for investigating aluminium based systems is the environmental constraints. This paper summarize the status on research of aluminium citrate gels. Several field experiments have been carried out, some of them claimed to be a success but yet the gelation mechanisms has not been fully understood. This paper demonstrates one possible gelation mechanism, where oligomerisation of the aluminium citrate complex is essential. The variation in gelation kinetic observed and to some extend gelation mechanisms for the different sources of aluminium is mainly because of the difference in oligomerisation. The ratio between aluminium and citrate is critical. In seawater, precipitation of aluminium is observed at low amount of citrate (2:1) and precipitation of calcium citrate at ratios above 1:2. Within this window robust gels may be formed as long as pH is below 6 and hydrolysed polyacrylamide are used. In core flopds gel is formed if the sources to polymer degradation is removed. At aluminium to citrate ratios of 1:1 no precipitation and face plugging, that is a severe problem at lower citrate concentrations, have been observed.